The contractor shall test under Good Laboratory Practice approximately 20 - 25 NCI-supplied and coded samples per year for their ability to induce mutations in the mouse lymphoma assays. Up to 5 samples per year will not be coded samples of chemical compounds but will be human urine specimens (single or pooled specimens). The contractor shall also test under Good Laboratory Practices, approximately 20 - 25 NCI-supplied and coded samples per year for their ability to induce mutations in Salmonella Typhimurium. Up to 5 samples per year will not be coded samples of chemical compounds but will be human urine specimens (single or pooled specimens).